From a228643e402d8f1fb07da88eba960ec368e23dda Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Mon, 9 Sep 2013 13:27:48 -0400
Subject: add can_change_{sample_rate,buffer_size}_while_running() methods to
 an AudioBackend

Allows the GUI and other stuff to know whether or not changing the SR/bufsize is possible while running, which is about to become useful
---
 libs/ardour/ardour/audio_backend.h      | 11 +++++++++++
 libs/backends/jack/jack_audiobackend.cc | 12 ++++++++++++
 libs/backends/jack/jack_audiobackend.h  |  3 +++
 3 files changed, 26 insertions(+)

diff --git a/libs/ardour/ardour/audio_backend.h b/libs/ardour/ardour/audio_backend.h
index 77b7eadb48..4192f0ea8b 100644
--- a/libs/ardour/ardour/audio_backend.h
+++ b/libs/ardour/ardour/audio_backend.h
@@ -147,6 +147,17 @@ class AudioBackend {
      */
     virtual uint32_t available_output_channel_count (const std::string& device) const = 0;
 
+    /* Return true if the derived class can change the sample rate of the
+     * device in use while the device is already being used. Return false
+     * otherwise. (example: JACK cannot do this as of September 2013)
+     */
+    virtual bool can_change_sample_rate_when_running () const = 0;
+    /* Return true if the derived class can change the buffer size of the
+     * device in use while the device is already being used. Return false
+     * otherwise. 
+     */
+    virtual bool can_change_buffer_size_when_running () const = 0;
+
     /* Set the hardware parameters.
      * 
      * If called when the current state is stopped or paused,
diff --git a/libs/backends/jack/jack_audiobackend.cc b/libs/backends/jack/jack_audiobackend.cc
index 22e5a525ea..f452a78d49 100644
--- a/libs/backends/jack/jack_audiobackend.cc
+++ b/libs/backends/jack/jack_audiobackend.cc
@@ -935,3 +935,15 @@ JACKAudioBackend::n_physical (unsigned long flags) const
 
 	return c;
 }
+
+bool
+JACKAudioBackend::can_change_sample_rate_when_running () const
+{
+	return false;
+}
+
+bool
+JACKAudioBackend::can_change_buffer_size_when_running () const
+{
+	return true;
+}
diff --git a/libs/backends/jack/jack_audiobackend.h b/libs/backends/jack/jack_audiobackend.h
index 5ba9ee63d7..f47b630f49 100644
--- a/libs/backends/jack/jack_audiobackend.h
+++ b/libs/backends/jack/jack_audiobackend.h
@@ -61,6 +61,9 @@ class JACKAudioBackend : public AudioBackend {
     uint32_t available_input_channel_count (const std::string& device) const;
     uint32_t available_output_channel_count (const std::string& device) const;
 
+    bool can_change_sample_rate_when_running() const;
+    bool can_change_buffer_size_when_running() const;
+
     int set_device_name (const std::string&);
     int set_sample_rate (float);
     int set_buffer_size (uint32_t);
-- 
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